In the prior known felt-tip pen, the felt tip is held in an intermediate piece exchangeably secured to the handle member, and is in abutting engagement with a reservoir structure inside the handle member. In this arrangement, the intermediate piece is of a tapering configuration in the direction of the felt tip. This enables the felt-tip pen to be inserted into a funnel-shaped opening of an inkwell until the tip of the felt tip takes support upon an absorbent body disposed in the inkwell. As a result of capillary action, the ink contained in the inkwell rises in the absorbent body, impregnating the felt tip resting thereon. Capillarity being also present in the felt tip, causing the ink to rise, the reservoir structure in the handle member becomes equally impregnated with ink. The supply of ink consumed by the felt-tip pen is thus replenished automatically during breaks between uses.
When the pen is inserted into the inkwell, it occurs frequently that the felt tip contacts the wall of the funnel, smearing it with ink. This ink is then directly transferred to the outside of the intermediate piece. When the user's fingers hold the felt-tip pen by the forward end in the area of the intermediate piece to resume writing, they will promptly become stained with ink.
A further disadvantage is that the felt-tip pen effects a poor seal or no seal at all when inserted into the funnel. In cases where an excessively narrow funnel is selected, the writing point fails to reach the absorbent body, the felt-tip pen being already stuck short of reaching it, in addition to being wedged considerably. Ink is then prevented from rising up into the felt-tip pen. It is also not possible to accurately match the dimensions of funnel, intermediate piece, length of the writing point and height of the absorbent body, because the writing point is exposed to wear in use, and the absorbent body expands to a greater or lesser degree, depending on the quantity of ink absorbed. In the known embodiment of the felt-tip pen, it is thus necessary ultimately to provide a specified gap between the funnel of the inkwell and the intermediate piece in order to ensure proper functioning. Considering, however, that the felt-tip pen is customarily inserted into the inkwell for storage also during prolonged periods of non-use, this gap logically causes the ink in the inkwell to dry out. Not only is ink thereby wasted uselessly, but the vaporization of the ink also changes its consistency, impairing or even ruining the writing quality and also the replenishment effect. Further, depending on the composition of the ink, noxious fumes are continuously released.
It is an object of the present invention to configure a felt tip pen device of the type initially referred to such as to effect a tight seal on insertion of the felt-tip pen into the opening of a congruent inkwell, without the felt-tip pen becoming wedged in the opening of the inkwell. It is a further object to configure the felt-tip pen in such a fashion as to prevent the outer contour of the felt-tip pen from becoming soiled with ink.
According to the present invention, this object is accomplished in that a groove concentric with the longitudinal axis of the felt tip is provided, the groove encompassing the felt tip immediately behind the protruding end of the felt tip and being open in the direction of this end, thus enabling the felt-tip pen to be introduced into an opening of an inkwell, in which process a collar encompassing the opening engages within the groove, the felt tip encountering an ink-impregnated absorbent body before the collar reaches the bottom of the groove. This embodiment ensures that ink smudges occurring at the opening of the inkwell are prevented from being transferred to the outer contour of the felt-tip pen, because at no time is this outer contour introduced into the opening. Yet, the felt-tip pen may be provided with a comparatively slim design, so that view of the writing point is not obstructed in use. In this arrangement, groove and collar of the inkwell may extend perfectly parallel to each other, with a small gap being maintained on both sides of the collar. This thus effectively avoids wedging of the felt-tip pen as it occurs in the prior-art felt-tip pen due to its conical intermediate piece. In spite of this gap, a tight seal is effected, because the gap between the collar of the inkwell and the felt-tip pen extends in U-shape, thus forming a labyrinth-type seal. For maximum length of the labyrinth, it will be advantageous to provide the groove with a depth which is a multiple of its width. The labyrinth effectively prevents the ink in the inkwell from drying out with the felt-tip pen seated in place. Moreover, if the collar on the inkwell is arranged in a cylindrical hollow whose inside diameter is only slightly greater than the outside diameter of the intermediate piece, a third sealing gap results enhancing the effect of the labyrinth still further. In this configuration, the labyrinth is S-shaped, without this increasing the material requirements for the wearing part of the felt-tip pen.
In the felt-tip pen constructed in accordance with the present invention, wear of the felt tip and/or the absorbent body is effectively compensated for. The relative distance of the groove bottom and the upper end of the collar can be amply dimensioned to compensate for differences. The effect of the labyrinth is even substantially improved by a large distance at this particular location, since changes of cross section are generally desirable in labyrinth seals in order to achieve the full effect.
For a felt-tip pen in which the felt tip is held in an intermediate piece exchangeably attached to the handle member and is in abutting engagement with a reservoir structure inside the handle member, it is another object to configure the intermediate piece such that the felt tip can be used with both of its ends, affords ease of manufacture and ready replacement.
This further object is accomplished in that the intermediate piece is comprised of an inner and an outer sleeve concentrically arranged with each other, with the sleeves being interconnected by a central link member such as to produce two equal grooves extending concentrically with the longitudinal axis of the felt tip disposed in the inner sleeve and protruding from both ends, and that the handle member is inserted into one of the grooves for locking engagement therein. The locking engagement can be accomplished simply by providing in the inner sleeve in the area of the link member an inwardly extending projection holding the inserted felt tip captive. The felt tip is then press-fitted into the intermediate piece. In addition, a particular advantage results if the felt tip extends from both ends of the intermediate piece by the same length and is configured as a writing end. This results in a perfectly symmetrical shape of the intermediate piece and the felt tip. The intermediate piece includes two identical grooves extending in opposite directions. With its first, upper groove, the intermediate piece is pushed onto the congruent handle member until the felt tip extending into the handle member engages the reservoir structure received therein. As this occurs, the locking engagement between the handle member and the intermediate piece is conveniently accomplished by a press fit. With its other groove, the intermediate piece is placed down onto the inkwell as described in the foregoing. When the first end of the felt tip extending out of the handle member of the pen is worn down, the intermediate piece holding the felt tip can be simply detached from the handle member and, using a turning motion through 180.degree., can be put back in place. Thus, the second end of the felt tip is available for use. With the embodiment of the present invention it is thus possible for the wearing part of the felt-tip pen, that is, the expensive felt tip and the intermediate piece to which it is attached, to be put to double use, resulting in a 50% savings of these parts aside from affording functional advantages.